Creating new and sustainable fuels to meet our world's ever growing energy demands is a national challenge. Catalysts with dissimilar selectivities to pure metal, or even bimetallic, conventional catalysts allow for more finely tuned reaction conditions that are more efficient and more profitable. The aim of the research was to show that catalysts containing fewer platinum group metals (PGM, by wt%) can have different, and enhanced, activity compared to the pure PGM catalyst.
Bimetallic overlayer catalysts were synthesized to show that the d-band center of the overlayer metal (Pt and Pd) can be changed via two effects: one electronic (ligand effect) and one physical (strain effect). The strain and ligand effects were studied via ethylene hydrogenation reactivity, FEFF computational studies, X-ray absorption spectroscopy (XAS), and chemisorption. Catalysts with specific strain and ligand characteristics were synthesized, including Ni@Pt (strain), Co@Pt (strain and ligand), Re@Pd (ligand), and Au@Pd (strain and ligand) catalysts. All overlayer catalysts were found to be capable of drastic changes in the overlayer metal d-band center as a result of ligand and strain effects. XAS was used to sample the overlayer metal d-band and demonstrated that the Pt and Pd d-bandwidths were changed via close interaction with the supported core metal (Re, Co, Ni, and Au) particles.